HIGH-RESOLUTION X-RAY-DIFFRACTION OF PERIODIC SURFACE GRATINGS

We show that very clear satellite peaks (up to the 22nd order) from periodic surface gratings in InP can be obtained in a rocking curve provided that the appropriate diffraction geometry is chosen. For (001) oriented Si, InP, or GaAs substrates with corrugations in the [110] direction, measured with CuKalpha1, the optimal geometry is best approximated by the 113 reflection measured with a high angle of incidence. Due to beam compression, caused by the asymmetry of the reflection, this reflection is also suited to obtain two-dimensional reciprocal space maps. A simple slit can be used to obtain adequate detector resolution. The maps reveal in detail the shape of the grating. They are compared with model calculations based on Fourier transformation of the shape of the grating-crystal assembly.